1. Field of the Invention
The present invention relates to a technique of non-contact communication between a device like a printing device and its expendable container.
2. Description of the Related Art
The application of non-contact tags to a data carrier has been proposed recently. Such a non-contact tag may be attached to, for example, an ink cartridge for inkjet printers. Some pieces of useful information, for example, the expiration date of ink, are stored in the non-contact tag. The printer main body acquires these pieces of information from an ink cartridge attached to the printer main body through electromagnetic-inducing communication. The electromagnetic-inducing communication may adopt the anti-collision function that allows for communication with multiple non-contact tags without collisions (interference).
The anti-collision function causes each command sent from the printer main body to include corresponding one among respective ID informations separately held by the multiple non-contact tags. Only a non-contact tag with the corresponding ID information responds to the command. The anti-collision function is on the premise that the printer main body has the respective ID informations on the multiple non-contact tags. The mapping of the ID information to the attachment position of each ink cartridge is also required for adequate user of the ink cartridge in the printer.
One proposed technique of the electromagnetic-inducing communication regulates the relative position of a non-contact tag attached to each ink cartridge to an antenna of the printer and the transmission output of the antenna, which cause sufficient electromagnetic induction only in a target non-contact tag, so as to acquire ID information of the ink cartridge with the target non-contact tag at each attachment position.
There is, however, a manufacturing variation in resonance frequency among multiple different resonance circuits included in non-contact tags. It is accordingly possible that a non-contact tag having a resonance frequency extremely close to the frequency of the transmission output of the antenna is located adjacent to a non-contact tag having a resonance frequency relatively apart from the frequency of the transmission output of the antenna.
In such cases, excess induced current flows in the antenna of the former non-contact tag and undesirably weakens the surrounding AC magnetic field. This may cause a potential problem that only an insufficient induced voltage is generated in the antenna of the non-contact tag adjoining to the former non-contact tag.
The enhanced transmission output of the antenna in the printer, on the other hand, causes another problem that the antenna of the printer may establish an unexpected communication with another non-contact tag that is not adjacent to the former non-contact tag. These problems are not restricted to the ink cartridges but are commonly found in any expendable containers that utilize non-contact tags for storage of information on expendables.